(1) Field of the Invention
The present invention relates to a wound core of a transformer to which cylindrical coil bobbins are applied and a method for manufacturing the same.
2) Description of the Related Art
As wound cores of transformers to which cylindrical coil bobbins are applied, circular cross sectional cores, which have advantages in that they are very thin, very small, and very light, the like, recently have been used (see: Japanese Examined Patent Publication (Kokoku) Nos. 60-28375 and 61-22851, and Japanese Unexamined Patent Publication (Kokai) No. 55-132027).
In the above-mentioned wound core, however, the beginning and end portions of a wound strip material may be deviated from the wound center thereof, and as a result, when a pressure welded coil bobbin is applied to the wound core and is rotated, the wound core scratches the inner surface of the coil bobbin, thereby seriously hindering the winding operation. Also, it sometimes becomes impossible to perform a pressure welding operation because the coil bobbin has split into two pieces, as explained later in detail.